DESCRIPTION: HIV/AIDS remains a global epidemic and public health threat. Despite the development of effective antiretroviral drugs, therapy is not curative and is therefore life-long. Long-term therapy is often compromised by viral drug resistance mutations and incomplete adherence. The HIV-1 capsid represents an attractive target for therapy, though currently available inhibitors lack sufficient potency for clinical development. This project will develop a competition-based assay for small molecules targeting a specific pocket in the HIV-1 capsid and will adapt the assay for high-throughput screening of large compound libraries. The assay will be validated by screening a library of 10,000 small molecules and analyzing the hits for antiviral activity and cytotoxicity. This work will facilitate the identification of lead compounds for development of antivirals targeting the HIV-1 capsid, and will identify novel probes for HIV-1 capsid function. Specific Aims: Aim 1. Establish a competition-based high-throughput screening assay for small molecules that bind the H3-H4 pocket in HIV-1 CA. Aim 2. Perform pilot screens to validate the assay. Aim 3. Test the confirmed hits for antiviral activity against wild type HIV- and mutant viruses that are resistant to known capsid inhibitors.